Friday, October 20, 2017

.NET Conf 2017

In case you missed .NET Conf 2017, all the videos are available online on Channel 9.


Thursday, October 19, 2017

SQL Server Full Text Search–Wildcards

The SQL Server Full Text Search option is really powerful. However you need to be aware that by default a search is always done on a full word. For example if you had indexed ‘the quick brown fox jumps over the lazy dog’ and you search for ‘brow’ you don’t get a result back.

To solve this you can use wildcards, but you have to be aware that you put the full search term between quotes.

This query will not work:

SELECT BookID,BookTitle

FROM Books

WHERE CONTAINS(BookTitle,'brow*')

But this query will:

SELECT BookID,BookTitle

FROM Books

WHERE CONTAINS(BookTitle,'"brow*"')

Wednesday, October 18, 2017

Angular i18n issue - Cannot read property 'toLowerCase' of null

After following the steps in the Angular documentation to setup internationalization(i18n) support, I tried to execute my brand new i18n npm command:

PS C:\Projects\test\AngularLocalization\angularlocal> npm run i18n

> angularlocal@0.0.0 i18n C:\Projects\test\AngularLocalization\angularlocal

> ng-xi18n

TypeError: Cannot read property 'toLowerCase' of null

    at Extractor.serialize (C:\Projects\test\AngularLocalization\angularlocal\node_modules\@an


    at C:\Projects\test\AngularLocalization\angularlocal\node_modules\@angular\compiler-cli\sr


    at process._tickCallback (internal/process/next_tick.js:109:7)

    at Module.runMain (module.js:606:11)

at run (bootstrap_node.js:389:7)

    at startup (bootstrap_node.js:149:9)

    at bootstrap_node.js:502:3

Extraction failed

npm ERR! Windows_NT 10.0.15063

npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\

npm\\bin\\npm-cli.js" "run" "i18n"

npm ERR! node v6.11.3

npm ERR! npm  v3.10.10


npm ERR! angularlocal@0.0.0 i18n: `ng-xi18n`

npm ERR! Exit status 1

npm ERR!

npm ERR! Failed at the angularlocal@0.0.0 i18n script 'ng-xi18n'.

npm ERR! Make sure you have the latest version of node.js and npm installed.

npm ERR! If you do, this is most likely a problem with the angularlocal package,

npm ERR! not with npm itself.

npm ERR! Tell the author that this fails on your system:

npm ERR!     ng-xi18n

npm ERR! You can get information on how to open an issue for this project with:

npm ERR!     npm bugs angularlocal

npm ERR! Or if that isn't available, you can get their info via:

npm ERR!     npm owner ls angularlocal

npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:

npm ERR!     C:\Projects\test\AngularLocalization\angularlocal\npm-debug.log

Whoops! This was not the output I was hoping for…

Strange! Because it worked perfectly before Confused smile. A search through the issues on GitHub brought me to the following issue:

The issue seems to have appeared in Angular 4.0.3. Luckily a workaround exists, I altered the commando in my package.json to include the prefered format:


When I invoked the i18n command again, this time it worked without a problem.

Tuesday, October 17, 2017

Impress your colleagues with your knowledge about…Expression Evaluator Format Specifiers

Sometimes when working with C# you discover some hidden gems. Some of them very useful, other ones a little bit harder to find a good way to benefit from their functionality. One of those hidden gems that I discovered some days ago are Expression Evaluator Format Specifiers.

What is it?

Expression Evaluator Format Specifies come into the picture when you are debugging in Visual Studio. The part of the debugger that processes the language being debugged is known as the expression evaluator (EE). A different expression evaluator is used for each language, though a default is selected if the language cannot be determined.

A format specifier, in the debugger, is a special syntax to tell the EE how to interpret the expression being examined. You can read about all of the format specifiers in the documentation.

One of really useful format specifiers is the ‘ac’ (always calculate) format specifier. This format specifier will force evaluation of the expression on every step. This is useful during debugging when you want to track a specific value.

How to use it?

  • Start a debugging session in your application.


  • Go to the Watch window(Debug –> Windows –> Watch –> Watch 1)


  • Write the expression that you want to check, a comma and the format specifier; {expression},{format specifier}


  • If you use the ac format specifier you don’t have to refresh your expression but will it be evaluated on every step:



Monday, October 16, 2017

Seeing the power of types

Most applications I’ve seen don’t take advantage of the power of the type system and fall back to primitive types like string, int, … .

But what if you start using the type system to design a more understandable and less buggy application?

You don’t believe it is possible? Have a look at the Designing with Types blog series, it will change the way you write your code forever…

The complete list of posts:

1. Designing with types: Introduction

Making design more transparent and improving correctness

2. Designing with types: Single case union types

Adding meaning to primitive types

3. Designing with types: Making illegal states unrepresentable

Encoding business logic in types

4. Designing with types: Discovering new concepts

Gaining deeper insight into the domain

5. Designing with types: Making state explicit

Using state machines to ensure correctness

6. Designing with types: Constrained strings

Adding more semantic information to a primitive type

7. Designing with types: Non-string types

Working with integers and dates safely

8. Designing with types: Conclusion

A before and after comparison

Friday, October 13, 2017

Angular: Analyze your webpack bundles

To optimize your application it can be useful to investigate all the things that are loaded and used inside your webpack bundles. A great tool to visualize this information is the webpack dependency analyzer:

From the documentation:

The Webpack dependency analyzer is a Webpack plugin and CLI utility that represents bundle content as convenient interactive zoomable treemap

webpack bundle analyzer zoomable treemap

This module will help you:

  1. Realize what's really inside your bundle
  2. Find out what modules make up the most of it's size
  3. Find modules that got there by mistake
  4. Optimize it!

How to use it inside your Angular app?

  • Install the bundle through npm:
    • npm install webpack-bundle-analyzer
  • Update your package.json with an extra command:
    • "analyze": "ng build --prod --stats-json && webpack-bundle-analyzer dist/stats.json"
  • Invoke the command through npm
    • npm run analyze
  • A browser window is loaded at

Thursday, October 12, 2017

IIS Server configs

If you are hosting your ASP.NET applications inside IIS I have a great tip for you:

This GitHub project contains a list of boilerplate web.config files applying some best practices(like security hardening) and taking maximal advantage of the powerfull functionality that IIS has to offer.

It shows and explains how to:

  • Apply security through obscurity by not exposing specific information through the headers
  • Apply GZIP compression on static content
  • Disable tracing
  • Secure your cookies
  • Cache static content
  • Support cache busting

Wednesday, October 11, 2017

ASP.NET Core–Environment variables

ASP.NET Core references a particular environment variable, ASPNETCORE_ENVIRONMENT to describe the environment the application is currently running in. This variable can be set to any value you like, but 3 values are used by convention: Development, Staging, and Production.

Based on this information the ASP.NET Core configuration system can load specific configuration settings (through .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true) )
or execute a specific Startup class or Startup method through the Startup conventions(e.g. a Startup{EnvironmentName} class or a Configure{EnvironmentName}() method inside the Startup class).

At one customer we are hosting our ASP.NET Core applications inside IIS. The IIS environment is used both for development and testing. So we want to host the same application twice with a different environment setting. By default the environment setting is loaded from a system level environment variable which of course can be set to only one value.

How can we solve this?

To support this scenario the ASP.NET Core Module inside your web.config allows you specify environment variables for the process specified in the processPath attribute by specifying them in one or more environmentVariable child elements of an environmentVariables collection element under the aspNetCore element. Environment variables set in this section take precedence over system environment variables for the process.

An example:

Tuesday, October 10, 2017

ASP.NET Core 2.0–Authentication Middleware changes

ASP.NET Core 2.0 introduces a new model for authentication which requires some changes when upgrading your existing ASP.NET Core 1.x applications to 2.0.

In ASP.NET Core 1.x, every auth scheme had its own middleware, and startup looked something like this:

In ASP.NET Core 2.0, there is now only a single Authentication middleware, and each authentication scheme is registered during ConfigureServices() instead of during Configure():

More information:

Monday, October 9, 2017

Angular 4.3: HTTP Interceptors are back

With the introduction of a new HttpClient in Angular 4.3, an old feature of Angular.js was re-introduced; HttpInterceptors. Interceptors are sitting between the application and the backend and allow you to transform a request coming from the application before it is actually submitted to the backend. And of course you when a response arrivers from the backend an interceptor can transform it before delivering it to your application logic.

This allows us to simplify the interaction with the backend in our Angular app and hide most of the shared logic inside an interceptor.

Let’s create a simple example that injects an OAuth token in our requests:

To be able to use the interceptor, you’ll have to register it:

Friday, September 29, 2017

Enabling Application Insights on an existing project

Yesterday I lost some time searching how to Enable Application Insights on an existing project in Visual Studio.

I thought it was available on the context menu when you right click on your Visual Studio project, but no option found there:


Turns out you need to go one level deeper Confused smile;

  • Right click on your project
  • Click on Add and select Application Insights Telemetry…


Now you can go through the configuration wizard by clicking on Start Free:


Thursday, September 28, 2017

Visual Studio 2017 Offline install - “Unable to download installation files”

After creating an offline installer for Visual Studio 2017 using vs_enterprise.exe --layout c:\vs2017offline we were ready to install Visual Studio on our build servers(which don’t have Internet access).

However when we tried to run the installer, it failed after running for a few minutes with the following error message:

Unable to download installation files

Unable to download install files

This error message was not that useful as we found out that the problem was not related to missing installation files but due to the fact that we forgot to install the required certificates first.

To install the certificates first, you have to

  1. Browse to the "certificates" folder inside the layout folder you created(e.g. c:\vs2017offline\certificates)

  2. Right-click each one and choose Install PFX.

  3. Specify Local machine as target certificate store
  4. Leave the password field empty

More information:

Wednesday, September 27, 2017

Team Foundation Server–Upgrade your build agents

If you upgrade your TFS installation to a newer version, a new version of the build agent is available as well.

To upgrade your agents, you have 2 options:

  • If a new major version of the agent is released, you’ll have to manually delete the old agent and install a new agent.
  • If a new minor version of the agent is released, the existing agent is upgraded automatically when it runs a task that requires a newer version of the agent.
    • If you want to trigger the update manually, you can go to the Agent Pool hub, right click on a Queue and click on Update All Agents.


More information at

Tuesday, September 26, 2017

NPGSQL–Relation does not exist

PostgreSQL has great .NET support thanks to the open source NPGSQL library.

From the home page:

Npgsql is an open source ADO.NET Data Provider for PostgreSQL, it allows programs written in C#, Visual Basic, F# to access the PostgreSQL database server. It is implemented in 100% C# code, is free and is open source.

In addition, providers have been written for Entity Framework Core and for Entity Framework 6.x.

However I immediately had some problems the moment I tried to execute a query. Strange thing was that my code almost the same as what could be found on the Getting Started page;

The error I got was the following:

Query failed: ERROR: relation "Northwind.Products" does not exist

I tried to execute the same query directly in the PGAdmin tool and indeed I got the same error.

What am I doing wrong? The problem is that PostgreSQL by default implicitly converts unquoted identifiers in my query to lowercase.

So the following query;

SELECT Id, ProductName FROM Northwind.Products

was transformed to

SELECT id, productname FROM northwind.products

As object names are case sensitive in PostgreSQL(or so it seems), this resulted in the fact that my table was not found.

There are 2 possible solutions:

  • Use quotes around your identifiers: SELECT “Id”, “ProductName” FROM “Northwind”.”Products”
  • Change the casing of your database objects(tables, columns, …) to lowercase

I choose the last option, because I had to escape my query in string in my C# code otherwise.

Monday, September 25, 2017

TypeScript error–Property ‘assign’ does not exists on type ‘ObjectConstructor’

A colleague asked me for help when he got into trouble with his TypeScript code. Here is a simplified version:

Although this looks like valid code, the TypeScript compiler complained:


After some headscratching, we discovered that there was a “rogue” tsconfig.json at a higher level that set “ES5” as the target. Object.Assign was added as part of “ES6” explaining why TypeScript complained.


After changing the target to “es6”, the error disappeared.

Friday, September 22, 2017

VSWhere.exe–The Visual Studio Locator

As someone who has built a lot if CI and CD pipelines, one of the struggles I always got when new Visual Studio versions were released was how to make my build server use the correct version of MSBuild when multiple Visual Studio versions were installed.

It got a lot better over the years, but even recently I was sitting together with a customer to investigate how we could make the build server understand that the Visual Studio 2017 Build tools should be used.

One of the (badly documented) tricks you could use was scanning the registry for specific registry keys. Luckily Microsoft released recently a new tool that makes finding your Visual Studio instances a lot easier: vswhere.exe

From the documentation:

vswhere is designed to be a redistributable, single-file executable that can be used in build or deployment scripts to find where Visual Studio - or other products in the Visual Studio family - is located. For example, if you know the relative path to MSBuild, you can find the root of the Visual Studio install and combine the paths to find what you need.

You can emit different formats for information based on what your scripts can consume, including plain text, JSON, and XML. Pull requests may be accepted for other common formats as well.

vswhere is included with the installer as of Visual Studio 2017 version 15.2 and later, and can be found at the following location: %ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe. The binary may be copied from that location as needed, installed using Chocolatey, or the latest version may be downloaded from the releases page. More information about how to get vswhere is on the wiki.

This tool is also used internally in the VSBuild build task in TFS to discover recent Visual Studio versions(2017 and newer).

A quick sample:

  • Open a command prompt
  • Browse to %ProgramFiles(x86)%\Microsoft Visual Studio\Installer\ or the location where you downloaded vswhere.exe.
  • Let’s try vswhere –latest


Thursday, September 21, 2017

.NET Standard: Using the InternalsVisibleToAttribute

In .NET Standard projects, there is an AssemblyInfo class built-in, so you no longer need a separate AssemblyInfo.cs file in your project Properties.

But what if you want to use the InternalsVisibleToAttribute? This was one of the attributes I used a lot to expose the internals of my Assembly to my test projects.

Turns out that it doesn’t matter really where you put this attribute. It is applied at the assembly level, so you can include in any source code file you like. Using the AssemblyInfo file was just a convenience.

So what I did, was creating an empty .cs file and add the following code:

Wednesday, September 20, 2017

.NET Standard: Duplicate 'System.Reflection.AssemblyCompanyAttribute' attribute

In a ‘classic’ .NET project, you have an AssemblyInfo.cs file.


This file contains all kind of information about your assembly

After upgrading a classic .NET project to .NET Standard, I started to get errors about some of the properties inside the AssemblyInfo.cs file:


A .NET Standard project already has the AssemblyInfo information built-in. So after upgrading you end up with 2 AssemblyInfo specifications, leading to the errors above.

The solution is to remove the original AssemblyInfo.cs file in the Properties folder.

Remark: If you want to change the assembly information, you now have to use the Package tab inside your Project Properties.


Tuesday, September 19, 2017

RabbitMQ–Configure access to Management portal

As mentioned in a previous post, it is probably a good idea to enable the RabbitMQ Management plugin to help you track what’s going inside your service broker.

Now if you try to access the Management plugin using the default guest account(which you should probably remove), outside the server itself, you get a ‘Login failed’ error.


Let’s fix this:

  • Logon to the server
  • Browse to the management portal using the localhost address: http://localhost:15762
  • Logon using the guest account


  • Click on the Admin tab and scroll to the Add a user section
    • Enter a Username and Password
    • Specify one or more Tags as a comma separated list. If you want to give full access, enter ‘administrator’.
    • Click on the Add user button


  • Now click on the newly created user in the user list


  • The set permission section is shown


  • Leave the default settings and click Set permission.
  • That’s it!

Remark: You can do the same steps using the command line tooling. For example, if you want to set the user tags, you can use

$ rabbitmqctl set_user_tags yourName administrator

Monday, September 18, 2017

RabbitMQ–Enable Management plugin

To simplify management and monitoring of your RabbitMQ Service Broker it is a good idea to install the management plugin(don’t expect anything fancy).

  • To install it, logon to the server where you installed RabbitMQ
  • Open a RabbitMQ command prompt


  • Enter the following command
    • rabbitmq-plugins enable rabbitmq_management
  • You’ll get the following log output

D:\Program Files\RabbitMQ Server\rabbitmq_server-3.6.12\sbin>rabbitmq-plugins en

able rabbitmq_management

The following plugins have been enabled:







Applying plugin configuration to rabbit@SERVER01... started 6 plugins.


  • If you want to access the portal from outside the server, you have to configure a firewall rule that allows TCP traffic on port 15672.


  • Remark: Notice that when you try to access the management portal from outside the server using the default guest account, it will not work. This is a security feature that is enabled by default. To solve that, we’ll create another account, but that’s something we cover in another blog post.

Friday, September 15, 2017

ASP.NET Core–Configuring a WCF service

In an ASP.NET Core application(using the full .NET framework) we had to consume a WCF service.

Should be easy right? Unfortunately it turned out that be more work than I expected. In a first post I explained the steps how to generate a Client Proxy, this post is about  setting the configuration.

WCF configuration can be a daunting beast with a lot of options and things that can go wrong. The code generated by the proxy hardcodes (some part) of the configuration in the WCF proxy and provides you a partial method to override it but that’s not the approach we want to take.

I know we’ll host the WCF service in IIS, so adding a web.config and putting the configuration logic over there sounds nice…

Let’s try that:

  • Open the generated proxy reference file  and remove the call to Service1Client.GetDefaultBinding() and Service1Client.GetDefaultEndpointAddress() in the constructor. (Note: this is only for testing purposes)


  • Right click on your ASP.NET Core project and add a web.config file.
  • Right click on the web.config and choose Edit WCF configuration.


  • Go to the Client section and choose Create a New Client…


  • Follow the steps through the Wizard. After completing it you should have something like this inside your web.config:
  • Let’s now try to create a client proxy instance and execute a call:
  • Unfortunately, this didn’t work and we end with an exception when we try to run our application:


  • If that doesn’t work, where should we put this configuration? (And yes, I know I can do everything through code but that is not what I want here).
    • An ASP.NET Core project is an executable behind the scenes. The only thing that IIS does is forward the request to Kestrel that invokes the DotNet process.
    • This executable has its own configuration file that is generated for you out of the box behind the scenes.


  • If you want to change this config, you have to add an app.config instead of a web.config to your project. Let’s just rename the file, rebuild our project and try again…


  • This time it works!


Thursday, September 14, 2017

ASP.NET Core–Connecting to a WCF service

In an ASP.NET Core application(using the full .NET framework) we had to consume a WCF service.

Should be easy right? Unfortunately it turned out that be more work than I expected.

  • I right clicked on my project and searched for an Add service reference… option. No luck, instead I saw a Connected Services section. Maybe that will do it?


  • I right clicked on the Connected Services section and choose Add Connected Service.


  • This opened up the Connected Services window but no option was available to connect to an existing WCF service Sad smile


  • Maybe the Find more services… link at the button will help me? This brought me to the Visual Studio Marketplace. And yes… a search for ‘WCF’ showed up a Visual Studio Connected Services plugin that allows to add a WCF Web service reference to .NET Core projects. Exactly what I needed.


  • I clicked on Download, closed Visual Studio after which the installer appeared and I could install the extension.
  • After the installation has completed, we can open up Visual Studio again, try Add Connected Services again. This time we see a 3th option appear:
    • Microsoft WCF Web Service Reference Provider – Preview


  • Click on it and you’ll get the same options you had before when using Add service reference…


Wednesday, September 13, 2017


I’m currently working at a client where are (finally) migration from DB2 to SQL Server. One of the things we encountered is that DB2 is using a different precision(6 digits) for their DateTime than SQL Server, so as part of the migration process we change all target dates on SQL Server to DateTime2 to not loose any data.

After migrating everything seemed to work until we tried to save an object through NHibernate to the database; we always got a StaleObjectStateException.

Problem was that we were using one of these DateTime columns for concurrency checks. As NHibernate by default expects a DateTime instead of a DateTime2 we lost some precision when hydrating the objects from the database. When we later on tries to persist our changes, the concurrency check will see that the DateTimes are different resulting in a StaleObjectStateException.

The solution was to change our mapping code to use DateTime2 instead.

Here is our (updated) Fluent NHibernate code:

And here is a similar example using the NHibernate XML mapping:

Remark: We also had a problem with the difference in precision in DB2(6 digits) and SQL Server (7 digits) but that is maybe for another post…

Tuesday, September 12, 2017

Can I retarget my libraries to .NET Standard 2.0?

With the release of .NET Core 2.0 and the .NET Standard 2.0 specification, it’s time to check if I can retarget some of my old libraries to .NET Standard 2.0.

The tool you need is the .NET Portability Analyzer:

After downloading and installing the Visual Studio extension, it is time to configure it first:

  • Open the project you want to analyze in Visual Studio
  • Go to Tools –> Options and click on the .NET Portability Analyzer from the left menu


  • Select your Target Platforms and the Output formats of the generated report and click OK.
  • Now you can right click on a specific project or your solution and choose Analyze Assembly/Project Portability.


  • After the analysis has completed you’ll get a report that contains a nice summary, a long list of details and a list of missing assemblies:




Monday, September 11, 2017

JSON.NET–Using a Custom Contract Resolver without loosing CamelCasing

For a project I’m working we created a custom ContractResolver to apply some localization magic before JSON data is send to the client.

Here is the code we are using:

Let’s try this code:


As you can see the ContractResolver does its job, only problem is that we loose the CamelCasing. Here is how you can fix it:

Let’s run our code again: